The objective of this project is to study age-related changes in electrical and mechanical properties of gastrointestinal muscle, and to attempt to relate these changes to motility disorders associated with aging. The specific aims of the project are: (1) To determine whether there is a decrease in electrical coupling between smooth muscle cells of lower esophagus and gastrointestinal tract of old animals as compared to their younger counterparts. This will be determined by tissue impedance studies, by means of which myoplasmic and junctional (nexal) impedances can be obtained. (2) To determine whether in vivo patterns of slow wave activity are altered in such a way as might account for certain types of age-related motility dysfunction. Data will be obtained by multiple suction electrode recordings from gastrointestinal tracts primarily of aging cats. (3) To determine whether age-related changes occur in patterns of colonic electrical and mechanical activity which could be responsible for the increased incidence of constipation and diverticular disease associated with aging. Isolated colons of cats and rats will be utilized in these studies. (4) To determine the effect of high bulk vs. low bulk diets on colonic motility of aging rats. Electrical and mechanical studies will be carried out on colons from animals living under dietary conditions which have been shown to be conducive to development of diverticulosis, in an attempt to elucidate some of the factors involved in the etiology of this age-related disease.